1. Field of Invention
The present invention relates to a latch, and more particularly to a mechanical latch assembly which is adapted to lock up a door, such as an oven door, to a main housing, such as an oven housing, in accordance with a temperature thereof.
2. Description of Related Arts
Conventional latch assemblies are widely utilized for locking a door, such as an oven door, to a main housing, such as an oven housing, for a wide variety of purposes. A main concern for such conventional latch assemblies is the safety issue in using them. For example, how to ensure that the door, such as the oven door, is kept securely locked to the main housing, such as the oven housing when, say, the oven is operating has become a pressing problem for engineers. The main difficulty is that while it is relatively easy to lock the door to the main housing, it is not that easy to prevent accidental or undesirable unlocking so that any heat treatment taking place inside the main housing may cause a great risk to the people nearby.
Moreover, it is generally difficult to coordinate the locking and unlocking with the operation of the main housing, so that in many circumstances, electronics apparatuses or some sorts of artificial intelligence have to be utilized for simply doing such a function. However, once such electronics apparatuses or artificial intelligence are employed, the overall purchasing and the running costs will inevitably rise.
As a matter of fact, there exists a conventional latch assembly which comprises a supporting base, a locking latch pivotally connected to a manual handle which is adapted to drive the locking latch moving between a locked position where the locking latch is arranged to engage with the door so as to lock up the door with the main housing, and an unlocked position where the locking latch is arranged to disengage with the door so as to dismantle any locking interaction between the door and the main housing.
Furthermore, this conventional latch assembly further comprises a mechanical lock piece pivotally connected to the supporting base for restricting a pivotal movement of the manual handle so as to lock up the locking latch in its locked position. Typically, this mechanical lock piece is actuated by some sorts of mechanical arrangements such as a spiral coil which is capable of distorting when subject to elevated temperature and restoring to its original shape when the temperature goes down to the original level. As such, the mechanical lock piece is adapted to move to lock up the manual handle in accordance with the temperature to which the mechanical lock piece is subjected.
A main disadvantage of this conventional latch assembly is that the performance of the spiral coil is generally unstable and cannot be accurately predicted. As a result, it may be that the response time of the spiral coil is too slow that the manual handle is still kept locked when it is necessary to open the door on which the latch assembly is engaged. Alternatively, it may be that the response time is too fast that the door cannot be safely locked.